The reason: The results in those three states don't reflect polls, according to J. Alex Halderman, one of three experts calling for the results of the election to be confirmed. No one was expecting Wisconsin, for example, to go to President-elect Donald Trump.

What's more, there's a large body of evidence that hacking electronic voting machines is possible, even though most experts agree it would be incredibly difficult to sway a national election through hacking. Such machines were used in various counties in all three states, Halderman points out.

Halderman says he knows of no evidence such a hack took place. Still, he argues a recount in some of the most closely contested states is worthwhile for peace of mind and to establish a precedent of routinely examining the paper backups that many electronic voting machines produce.

"I believe the most likely explanation is that the polls were systematically wrong, rather than that the election was hacked," Halderman, a professor of computer science at the University of Michigan, wrote in a blog post on Medium. "But I don't believe that either one of these seemingly unlikely explanations is overwhelmingly more likely than the other."

That's where some statisticians and elections experts disagree.

Nate Cohn, a reporter at The New York Times who covers polling and demographics, and Nate Silver, who runs the polling statistics website FiveThirtyEight, both say the differences between the polls and the results don't point to any irregularities.

David Becker, an elections expert who has consulted with many voting officials throughout the US, said hacking is a less likely explanation for the surprise election outcome than bad polling is.

What's more, he says the logistics of picking the best states to target and hacking their closely guarded -- albeit flawed -- electronic voting machines would be "Herculean." The process would also include guessing the right number of votes to flip from Hillary Clinton to Trump.

"You can't be sitting in your mom's basement in Moscow and do this," said Becker, who is the executive director of the Center for Election Innovation and Research.

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Two of the three states in question -- Wisconsin and Pennsylvania -- have already begun required audits of their elections. An audit checks the results of a random sample of voting machines to make sure the technology is working the way it should.

Becker said if the audits don't catch any anomalies, a hack is extremely unlikely. The other computer security experts working with Halderman to challenge the election results called specifically for audits rather than recounts in an opinion piece in USA Today.

"A full manual recount of the paper records would be definitive, but that's unnecessarily difficult, expensive and time-consuming if the results are actually right," Ron Rivest of MIT and Philip Stark of UC Berkeley wrote in the op-ed.

Stein, who garnered 1 percent of the popular vote, has seen her fundraising appeal for a recount go viral and raised more than $1.1 million of her $2.5 million goal. She has until Friday to start filing the recount requests.

"We hope to do recounts in all three states," the Stein campaign's appeal reads. "If we only raise sufficient money for two, we will demand recounts in two states. If we only raise enough money for one, we will demand a recount in one state."

The Trump and Clinton organizations didn't respond to a request for comment.